Transcript Document

Meta-model based system design
Gábor Privitzky
[email protected]
Gábor Zsolt Nagy
[email protected]
Table of contents
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Today’s software design
Analysis and design
Elaboration modeling approach
Meta-models
Translation modeling approach
Experiences at Ericsson Hungary
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MDA applied in Ericsson Hungary
• MDA related activities since beginning of 2002
• Technology evaluation projects
• Development of a C++ code generator
– SNMP capabilities (network configuration protocol)
– CORBA notification service
– Trace, debug capabilities
• Development of 2 sub-systems of a 3G mgmt. System
– 90% of code was generated!
• Common service domains (XML, Logging, etc.)
• TTCN test bed, XMI export, HTML doc. generator, etc.
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Today’s software design
• Productivity problems
– Labor intensive
– Rework
• Portability problems
– Emerging technologies
– Heterogeneous implementation techniques
• Maintenance problems
• Quality problems
• Changing requirements
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Traditional software development life cycle
Requirements
Text
Analysis
Text and
diagrams
Design
Text and
diagrams
Coding
Code
Testing
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Traditional software development life cycle
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Productivity problems
• Tedious programming tasks
• Late feedback
Requirements
Text
Portability problems
• Non-formalized analysis
• Design and Analysis are not separated
• Decisions are made in coding
Maintenance
• Shortcuts
• Documentation overhead
Quality problems
• Non-formalized
knowledge in heads
Analysis
Text and
diagrams
Design
Text and
diagrams
Coding
Code
Testing
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Way of writing specifications
• Textual specification
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ambiguous
difficult to verify
difficult to keep up-to-date
“we will sort it out during the design”
• Graphical specifications
– no semantic meaning defined
– undefined relations between diagram types
– difficult to verify
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Expectations
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Formalized way of specification
Early verification and testing
Separate business logic analysis and implementation
Software reuse
Leverage the initial investment in an early phase
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Analysis and Design
• Analysis
– Defines what to do; application business logic
– Captures requirements and functional decisions in a platform
independent manner
– Results in a Platform Independent Model (PIM)
• Design
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Defines how to do
Captures characteristic and interface requirements
Defines a specific platform (e.g. C++, Solaris, .NET, J2EE)
Results in a Platform Specific Model (PSM)
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PIM and PSM
• PIM (Platform Independent Model)
Expresses only business functionality and behavior
Director
1
directed by
0..*
directs
Movie
0..*
acts in
0..*
played by
Actor
• PSM (Platform Specific Model)
Defines also technology-specific details
e.g. Chained list, index tables
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MDA software development life cycle
Requirements
Text
Analysis
PIM
Design
PSM
Coding
Code
Testing
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What is Model Driven Architecture?
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MDA is an object-oriented software development method
Splits platform independent and platform specific decision
Holds decisions in models instead of documents
Based on Unified Modeling Language
2 approaches:
– Elaboration (model refinement)
– Translation
• CASE tools that support software life-cycle
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Elaboration approach
• Elaborationist approach
– middleware independence, an open, vendor neutral approach for
interoperability
– Booch, Rumbaugh and Jacobsen with UML
– OMG, Rational
– profiles
PIM
• Translationist approach
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PSM
Code
platform independence
Steve Mellor and Sally Shlaer
meta-model based tools
xUML
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Elaboration approach
Modeling structure (classes, attributes & associations)
Aids :
Use Case Diagramming
Sequence Diagramming
Collaboration Diagramming
Modeling behavior (FSMs)
Step 1 : During ‘analysis’, construct a model of the
user application
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Elaboration approach
… elaborate the model
Step 2: During ‘design’, add control structures, data
structures, GUI concepts, tasking mechanisms etc.
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Elaboration approach
e.g. C++ header files (.h)
Step 3 : Automated code generation converts
structural model elements to target language
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Elaboration approach
e.g. C++ program files (.cpp)
Step 4 : Behavioral code is added manually, introducing
model and code maintenance management demands.
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Problems of elaboration approach
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PSM is an extended PIM
New model elements are sprinkled into the PIM
Some model elements removed, merged or split apart
Destroys the original PIM
Platform specific elements may seep into PIM
Boundary between PIM and PSM is fuzzy
It often needs reverse engineering
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Platform independent models using MDA
• Elaborationist view
– middleware independence, an open, vendor neutral approach for
interoperability
– Booch, Rumbaugh and Jacobsen with UML
– OMG, Rational
– profiles
• Translationist view
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platform independence
Steve Mellor and Sally Shlaer
meta-model based tools
xUML
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PIM
Code
PSM
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How does translation work?
• OOA models can be
simulated before
implementation
• OOA models are
translated by Model
Compilers
Characteristic
and platform
specific
Requirements
Simulator
OOA
Model
Model
Translator
Source
Code
Functional
Requirements
Test
Cases
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Test
Suits
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Meta-modeling concept
• The “meta” prefix
– indicates one level of abstraction higher than root
– is used in a relative manner
• A meta-model is a model of a model
• The concept can be recursively applied to itself
– a meta-meta-model is a model of a meta-model
– a meta-meta-meta-model is a model of a meta-meta-model … 
• Meta-models are often defined for specific technology
domains
• OMG is now using M0-M3 notation for modeling
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Meta layers
M0 : User Objects
{“Pulp Fiction”, 1994, “Quentin Tarantino”}
{“Peter Smith”, 2004.12.23}
Populates
M1 : Model
Defines
Director, Actor, Movie
Populates
M2 : Meta-model
Defines
Class, Attribute,
Association
Populates
M3 : Meta-meta-model
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Defines
MOF::Class,
MOF::Attribute
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Self recursive description
• Concepts:
M2 (DSL)
– Class
– Attribute
– Relationship
M3
Attribute
Class
0..*
• name
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1
0..*
Relationship
1
• name
• description 1
0..*
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• side A multiplicity
• side B multiplicity
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Potential of meta-modeling
• Help others understand the problem domain by using the
same language
• Define a vocabulary for the elements in the problem
domain
• Manage complexity by raising the level of abstraction at
which we think and design
• Enables to develop solid knowledge-base in centralized
model repositories
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Model translation
How does PIM meta-model describes a system?
Domain
Class
State
Transition
Attribute
How does C++ meta-model describes a system?
Attribute
Parameter
Class
Function
Operation
Constructor
What is the system
architecture ?
AMD
domain
Client
Actor
Active_alarm
actor_ID
alarm_ID
problem_cause
...
IP_address
Destructor
What are the characteristic requirements ?
What is the task?
To create an Network_element
alarm handling application
client_ID
acknowledge
cease_alarm
factory
IP_address
ne_ID
create_alarm
cease_alarm
factory
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Model translation
How does PIM meta-model describes a system?
Domain
Class
State
AMD
Actor
Active
alarm
Client
Network
element
Operation
Transition
Attribute
cease
cease
alarm
alarm
Actor
Active_alarm
actor_ID
alarm_ID
problem_cause
...
IP_address
Client
Network_element
client_ID
IP_address
ne_ID
acknowledge
cease_alarm
factory
Parameter
Function
Constructor
What is the system
architecture ?
IP
address
factory
factory
Attribute
Class
actor_ID
alarm ID
client ID
IP
address
problem
cause
ne ID
acknowledge
create
alarm
AMD
domain
How does C++ meta-model describes a system?
Destructor
What are the characteristic requirements ?
create_alarm
cease_alarm
factory
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Model translation
How does PIM meta-model describes a system?
Domain
Class
State
AMD
Actor
Active
alarm
Client
Network
element
AMD
Attribute
Operation
Class
actor_ID
alarm ID
client ID
IP
address
problem
cause
ne ID
cease
cease
alarm
alarm
Actor
Active_alarm
actor_ID
alarm_ID
problem_cause
...
IP_address
Client
Network_element
client_ID
IP_address
ne_ID
Model
Translation
Parameter
Actor
Active
alarm
Client
Network
element
Constructor
What is the system
architecture ?
IP
address
factory
factory
acknowledge
cease_alarm
factory
Attribute
Transition
acknowledge
create
alarm
AMD
domain
How does C++ meta-model describes a system?
Function
acknowledge
create
alarm
cease
cease
alarm
alarm
actor_ID
alarm ID
client ID
IP
address
Destructor
problem
cause
ne ID
What are the
IP characaddress
requirements
?
factory
teristic
factory
create_alarm
cease_alarm
factory
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Model translation
How does PIM meta-model describes a system?
Domain
Class
State
AMD
Actor
Active
alarm
Client
Network
element
Operation
Attribute
Active_alarm
actor_ID
alarm_ID
problem_cause
...
IP_address
Network_element
client_ID
IP_address
ne_ID
Constructor
Destructor
What are the characteristic requirements ?
C++ source code
Actor
Client
Function
Model
Translation
What is the system
architecture ?
IP
address
factory
factory
Parameter
Class
actor_ID
alarm ID
client ID
IP
address
problem
cause
ne ID
cease
cease
alarm
alarm
acknowledge
cease_alarm
factory
Attribute
Transition
acknowledge
create
alarm
AMD
domain
How does C++ meta-model describes a system?
create_alarm
cease_alarm
factory
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Translation process
PIM
M-M
Defined
mapping
PSM
M-M
Defined
mapping
Generates
Populates
PIM
PSI
M-M
Applied
mapping
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PSM
Applied
mapping
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PSI
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Benefits of translation approach
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Early verification and testing
Separates business logic analysis and implementation
Software reuse
PSM and PIM are independently maintained
Leverage the initial investment in an early phase
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Platform independent
business logic
App2
App1
App3
Model
Compiler for
Platform v1
Platform v1
App1
App3
App2
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Platform independent
business logic
App2
App1
App3
Model
Compiler for
Platform v2
Platform v1
App1
App3
App2
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Platform v2
App1
App3
App2
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Potential of model translation
• Code generation is just one possibility
• Architectures can be used for:
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Document generation
Model verification
Model simulation
KPI measurements
Building architectures
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Model translation techniques
• Template based translation
– Source code templates extended with model queries
• Model based translation specified with
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ASL
QVT
XSLT
some other query language
• Code generation can be preceded by several model-tomodel translations
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Traditional software development life cycle
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Productivity problems
• Tedious programming tasks
• Late feedback
Requirements
Text
Portability problems
• Non-formalized analysis
• Design and Analysis are not separated
• Decisions are made in coding
Maintenance
• Shortcuts
• Documentation overhead
Quality problems
• Non-formalized
knowledge in heads
Analysis
Text and
diagrams
Design
Text and
diagrams
Coding
Code
Testing
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MDA software development life cycle
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Productivity problems
• Keeping intellectual property in models
and architectures
• Automated code generation
• Early verification
Portability problems
• Splitting platform specific and
platform independent decisions
Maintenance
• Strict forward engineering technique
• Documents and code are generated
• No data redundancy
Quality
• Uniform code quality
• Early verification
Requirements
Text
Analysis
PIM
Design
PSM
Coding
Code
Testing
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Project timelines
Traditional
Kick-off
MS1
Kick-off
MS1
MS3
MS2
MS2
MS3
MS4
MS4
MDA
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Activity distribution of an MDA project
Other activities
11%
Testing
12%
Analysis
49%
Implementation
28%
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Trend diagram of an MDA project
MHR
160
140
Analysis
120
Implementation
100
Testing
80
60
40
20
0
Week
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KPI comparison of “traditional” and MDA proj.
Traditional
MDA
Implemented requirements
48 %
83 %
Not implemented requirements
52 %
18 %
Cost (mhrs)
6800
3440
0
12
37
7
0
2
Analysis TRs
Implementation TRs
Architecture TRs
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Experiences
• MDA is not a “silver button”.
Doesn’t solve anything from itself…
• …but offers a strict process with technology support
• Using iterations. At feedback every affected part is
modified
• Sometimes difficult to decide between architecture and
application modeling
• Loosely connected areas (requirements, legacy codes) are
hard to keep consistent
• Model tests replaces basic and function tests (partly)
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Effects on the organization
• Introduction of new technology needs initial investment
– Time and money
– Gradual technology shift
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Fear and resistance from management side
Strong resistance from sw. developer side
High expectations
Balance of employees’ competence portfolio must change
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Conclusion
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It works!
Doesn’t solve everything
Reduces budget and time-to-market significantly
Offers uniform quality (for generated part)
Replaces textual documentation
Can keep different areas consistent but it’s not trivial
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Requirement analysis
Sw analysis, design and implementation
Testing
Quality measurements, project tracking
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Questions ?
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